ATR spectra of hair. Closest match with the database is keratin
Prior to each FT-IR measurement, a microscopy picture of the region of interest is acquired, as shown in the figure below. The region which is illuminated by the IR probe light is manually adjusted, here shown as red rectangles on several spots of the particle to be analysed. Apertures are automatically set within the device in order to fit these manual adjustments. Thus, the probe light exposes only the pre-set field of measurement.
All length scales for FT-IR microscope picture in this report are measured in microns, as marked in the figure below.
The quality indicates the match of the measured IR spectrum with a corresponding spectrum from a database. The higher the quality value, the better the match. Quality ranking: < 500: low quality, 500 - 700 middle quality and ≥ 700: high quality. Quality 1000 is the optimum match.